Pleated trocar seal

ABSTRACT

A trocar seal comprising an elastomeric membrane having an opening adapted to receive a surgical instrument. The membrane is configured with a plurality of pleats circumscribing the opening and extending laterally from opening. The pleats comprise a plurality of pleat walls increasing in height as the pleats extend laterally from the opening. In one embodiment, the pleats are conically arranged.

BACKGROUND

The present invention relates in general to endoscopic surgicalprocedures, and in particular, to trocars used in such procedures.

The use of endoscopic procedures in surgery has become widely accepted.The term “endoscopic” refers to all types of minimally invasive surgicalprocedures including laparoscopic and arthroscopic procedures.Endoscopic surgery has numerous advantages compared to traditional opensurgical procedures, including reduced trauma, faster recovery, reducedrisk of infection, and reduced scarring.

Numerous endoscopic instruments have been developed that allow thesurgeon to perform complex surgical procedures with minimal incisionsinto the skin and tissue surrounding a particular body cavity oranatomical region. In order to introduce the endoscopic instrumentationinto the body cavity, a device known as a “trocar” is often used topuncture and/or cannulate the wall of the body cavity. Trocars arewidely known in the art and typically comprise an obtruator and acannula. The obtruator typically includes a sharply pointed orappropriately structured tip that facilitates penetration of the bodycavity wall. The cannula provides a channel or opening through the bodycavity wall through which endoscopic instruments may be introduced andremoved by the surgeon.

Endoscopic surgery is often performed with an insufflatory fluid presentwithin the body cavity, such as carbon dioxide or saline, to provideadequate space to perform the intended surgical procedures. Theinsufflated cavity is generally under pressure and is sometimes referredto as being in a state of pneumoperitoneum. It is common for a sealingarrangement or seal assembly to be used in association with the trocarto maintain pneumoperitoneum. The seals will generally prevent theinsufflatory fluid from escaping while an endoscopic instrument ispositioned in the trocar cannula.

No one has previously made or used a trocar or seal in accordance withthe present invention.

BRIEF DESCRIPTION OF DRAWINGS

While the specification concludes with claims which particularly pointout and distinctly claim the invention, it is believed the inventionwill be better understood from the following description taken inconjunction with the accompanying drawings illustrating somenon-limiting examples of the invention. Unless otherwise indicated, thefigures are drawn to scale and like reference numerals identify the sameelements.

FIG. 1 depicts a cross-sectional view of a trocar;

FIG. 2 depicts an exploded view of the trocar of FIG. 1;

FIG. 3 depicts a perspective view of an instrument seal and bellows;

FIG. 4 depicts a cross-sectional view from FIG. 3; and

FIG. 5 depicts another cross-sectional view from FIG. 3.

DETAILED DESCRIPTION

FIG. 1 depicts a cross-sectional view of a trocar (10). During typicaluse the distal end (14) will be inserted through the body wall into thecavity, and the proximal end (12) will be positioned outside thepatient. A cannula (16) opens through the distal end (14) and is influid communication with a seal housing (18). The size of the cannula(16) can vary widely, but in the present example the inside diameter isabout 12.9 mm. A valve (20), shown here as a stopcock, permits thesurgeon to selectively introduce or relieve pressurized insufflationfluid through the trocar (10) to the body cavity. Optionally, the trocar(10) may include an obtruator (not shown).

The seal housing (18) contains a seal arrangement comprising a closurevalve (40) and an instrument seal (80) that work together to maintainpneumoperitoneum. In this example, the closure valve (40) is asingle-silted “duck bill” valve; however, other types of closure valvesmay also be used, including flapper valves, multi-silted duck billvalves, and the like. When an endoscopic instrument is passed though theproximal end (12) through the closure valve (40), the valve will openbut will generally not provide a complete seal against the instrument.When the instrument is removed from the trocar (10), the closure valve(40) closes and substantially prevents insufflation fluid from escapingthrough the trocar (10). The instrument seal (80) seals against theinstrument to prevent insufflation fluid from escaping through thetrocar (10); however, the instrument seal (80) generally will notmaintain pneumoperitoneum unless an instrument is positioned in thetrocar (10). In this example, the instrument seal (80) “floats”withinthe valve housing (18) such that the seal (80) can move laterallyrelative the trocar (10) centerline.

FIG. 2 depicts an exploded view of the trocar (10) and helps illustratethe assembly of the component parts. The lower body (30) includes anelongate tube portion (32), which defines the cannula (16), and ahousing portion (34). The upper body (110) attaches to the housingportion (34), which together provide a housing wall to define the sealhousing (18). The closure valve (40) is positioned and seated in thehousing portion (34). The retainer ring (50) is positioned and seatedagainst the closure valve (40) and sandwiches a flange on the closurevalve (40) against the housing portion (34) to provide a seal at thatlocation. These components can be made from a variety of differentmaterials. For instance, in the present example the lower body (30),retainer ring (50), and upper housing (110) are formed from relativelyrigid plastic such as polycarbonate, and the closure valve (40) isformed from a relatively soft elastomer such as polyisoprene; however,other materials could also be used.

The instrument seal assembly (120) is sandwiched between the retainerring (50) and the upper body (110) to provide a seal at that location.The instrument seal assembly (120) includes an anchor (60), bellows(70), instrument seal (80), protectors (90), and retainer (100). Theposts on the retainer (100) align with the corresponding holes on theother components of the assembly (120). The bellows (70), instrumentseal (80), and protectors (90) are sandwiched between the retainer (100)and the anchor (60). An interference fit between the retainer (100)posts and anchor (60) holes keep the assembly (120) in compression. Theprotectors (90) comprise four sequentially overlapping plates to protectthe instrument seal (80) from perforating or tearing due to surgicalinstruments. The components of the instrument seal assembly (120) can bemade from a variety of different materials with a range of differentmaterial properties. For instance, in the present example the anchor(60) and retainer (100) are formed from relatively rigid plastic such aspolycarbonate, the bellows (70) and instrument seal (80) are formed froma relatively soft elastomer such as polyisoprene, and the protectors(90) are formed from a pliant but semi-rigid plastic such as pellathane;however, other materials could also be used.

FIGS. 3-5 illustrate the bellows (70) and instrument seal (80). Thebellows (70) are an elastomeric membrane comprising a circular lateralflange (74), a circular medial flange (76), and circumferential pleats(72) positioned between the flanges (74, 76). The pleats (72) providelateral pliancy so the assembly (120) can float. The medial flange (76)includes a plurality of holes (77) that align with the retainer (100)posts. The lateral flange engages the housing wall creating a seal atthat location.

The instrument seal (80) is an elastomeric membrane having lips (82)defining an opening (81) adapted to receive and sealingly engage anendoscopic surgical instrument. The size of the opening (81) in itsrelaxed state may vary widely, but in the present example the insidediameter is between 3.8 and 4.0 mm. The instrument seal (80) of thepresent example is sufficiently elastic that the opening (81) can expandto sealingly engage instruments having diameters of up to 12.9 mm. Aplurality of pleats (89) circumscribe the opening (81) and extendlaterally from opening (81). As shown in this example, the instrumentseal (80) comprises eight linear pleats (89); however, greater or feweror non-linear pleats could also be used. In this embodiment, the pleats(89) are conically arranged. A wall section (85) circumscribes and isconnected to the pleats (89). As shown here, the inside diameter of thewall section (85) is between 17.7 and 17.9 mm. A radial flange (86)extends laterally from the wall section (85) and includes a plurality ofholes (87) that align with the retainer (100) posts.

Each pleat (89) comprises a pleat wall extending between the pleat peak(84) and pleat valley (83). The height of the pleat walls can bemeasured along the wall surface from the peak (84) to the valley (83).As shown here, the pleat walls each have a variably height that tapersmedially. Accordingly, the pleat walls increase in height as the pleatsextend laterally from the opening (81). Among other advantages, thepleats (89) help to reduce hoop stresses when an instrument ispositioned in the opening (81), thus reducing friction between theinstrument and the trocar (10). Reduced hoop stresses facilitate athicker wall thickness to be used while providing similar or reduceddrag forces than non-pleated lip seal designs, thus increasing sealdurability.

Optionally, the geometry of the pleats (89) can be designed to minimizeor eliminate hoop stress in the pleated portion of the seal (80) when aninstrument is introduced. In one embodiment, this geometric relationshipconforms to the following equation:

$h \geq {\frac{\pi}{P}\sqrt{r^{2} + r_{i}^{2} - r_{id}^{2}}}$

where:

-   -   h=pleat wall height as a function of radius    -   r=radius    -   r_(i)=radius of largest instrument designed for insertion        through seal    -   r_(id)=radius at inside diameter of pleat section of seal    -   P=number of pleats

A pleat design will substantially conform to the this equation if itcomplies with the essence of this equation, even if the pleat geometryvaries insignificantly. For example, geometric variances to accommodatemolding or other manufacturing considerations would substantiallyconform to this equation. As another example, a pleat design thatsatisfies the equation at all locations excepts for minor variances atthe inside or outer diameters of the pleat section of the seal wouldnevertheless substantially conform to the equation.

As shown in the figures, the pleats (89) form a generally frustoconicalshape bounded by the wall section (85) and the lip (82). In thisexample, the slope of the frustoconical shape is greater on the proximalside than the distal side, with both the proximal and distal surfacessloping distally toward the opening (81). Alternatively, both surfacescould slope proximally. In another variation, the proximal surface couldslope distally and the distal surface could slope proximally. In yetanother variation, one of the surfaces could slope while the other couldbe planar. It is also contemplated that both the surfaces could have thesame slope or both could be planar.

The lip (82) in this example has a cylindrical portion, which whenintersected with the pleats (89) results in a crown-shaped surface withproximally pointing tips corresponding to each peak (84). Similarly, thewall section (85) in this example has a cylindrical portion, which whenintersected with the pleats (89) results in an upside crown-shapedsurface with distally pointing tips corresponding to each valley (83).Naturally, the lip (82) and/or wall section (85) could benon-cylindrical, such as having a straight or curved taper.

The lateral flange (74) is compressed between the retainer ring (50) andthe upper body (110) to provide a seal against the housing wall. Themedial flange (76) and radial flange (86) are compressed between theanchor (60) and the retainer (100) to provide a seal. When an instrumentis positioned and sealed in the opening (81), pneumoperitoneum can bemaintained. While the bellows (70) and instrument seal (80) are shown inthis example as separate parts, it is contemplated that the bellows (70)and instrument seal (80) can be formed as a unitary part.

Preferably, the trocars will be processed before surgery. First, a newor used trocar is obtained and if necessary cleaned. The trocar can thenbe sterilized. In one sterilization technique, the trocar is placed in aclosed and sealed container, such as a plastic or TYVEK bag. Thecontainer and trocar are then placed in a field of radiation that canpenetrate the container, such as gamma radiation, x-rays, or high-energyelectrons. The radiation kills bacteria on the trocar and in thecontainer. The sterilized trocar can then be stored in the sterilecontainer. The sealed container keeps the trocar sterile until it isopened in the medical facility.

Having shown and described various embodiments and examples of thepresent invention, further adaptations of the methods and apparatusesdescribed herein can be accomplished by appropriate modifications by oneof ordinary skill in the art without departing from the scope of thepresent invention. Several of such potential modifications have beenmentioned, and others will be apparent to those skilled in the art. Forinstance, the specific dimensioned described above will be understood tobe nonlimiting examples. Accordingly, the scope of the present inventionshould be considered in terms of the following claims and is understoodnot to be limited to the details of structure, materials, or acts shownand described in the specification and drawings.

1. A seal for endoscopic instruments, comprising an elastomeric membranehaving an opening adapted to receive a surgical instrument, saidmembrane being configured with a plurality of pleats circumscribing theopening and extending laterally from opening, said pleats comprising aplurality of pleat walls increasing in height as the pleats extendlaterally from the opening; and wherein the pleat height substantiallyconforms to the following equation:$h \geq {\frac{\pi}{P}\sqrt{r^{2} + r_{i}^{2} - r_{id}^{2}}}$ where: h=pleat wall height as a function of radius r =radius r_(i)=radius oflargest instrument designed for insertion through seal r_(id)=radius atinside diameter of pleat section of seal P=number of pleats.
 2. The sealof claim 1, wherein the pleats are conically arranged.
 3. The seal ofclaim 1, further comprising a wall section circumscribing and connectedto the pleats.
 4. The seal of claim 3, wherein the wall section iscylindrical.
 5. The seal of claim 3, further comprising a radial flangeextending laterally from the wall section.
 6. The seal of claim 3,further comprising bellows circumscribing and connected to the wallsection.
 7. The seal of claim 1, further comprising a lip defining theopening.
 8. The seal of claim 1, comprising only eight pleats.
 9. Atrocar comprising the seal of claim
 1. 10. A method for processing atrocar for surgery, comprising: a) obtaining the trocar of claim 9; b)sterilizing the trocar; c) storing the trocar in a sterile container.